How long should dh prepare?

I've started my dh on supplements and making sure we dtd on a regular basis. Should this be done at least 70 days before our first attempt?

Sorry, I'm flooding this board with my crazy questions. I really want to do everything right this time.

Is there anything else I should have him do? He eats pretty healthy. He usually tries to consume a lot of protein but might not eat a lot of calories. He also does sit-ups/crunches/planks/push-ups on a daily basis. Our neighbor is giving us their bowflex so he's going to start using that too.

Yes as far in advance as possible for him. 72 days is about the lenght of time for sperm to form.

Do not let him overdo with the exercise - moderate only with lots of time to rest in between. And wear loose or even NO underwear while lifting if possible